The invention herein described relates generally to cushioning conversion machines and more particularly to improvements in the mechanisms for cutting cushioning materials formed by such machines.
In the process of shipping an item from one location to another, protective packaging material is often placed in the shipping container to fill any voids and/or to cushion the item during the shipping process. Some commonly used protective packaging materials are plastic foam peanuts and plastic bubble pack. While these conventional plastic materials seem to perform adequately as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and plastic foam peanuts is their effect on our environment. Quite simply, these plastic packaging materials are not biodegradable, and therefore they cannot avoid further multiplying our planet""s already critical waste disposal problems. The non-biodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility.
The foregoing and other disadvantages of conventional plastic packaging materials have made paper protective packaging material a very popular alternative. Paper is biodegradable, recyclable and composed of a renewable resource; making it an environmentally responsible choice for conscientious shippers.
While paper in sheet form could possibly be used as a protective packaging material, it is usually preferable to convert the sheets of paper into a relatively low density pad-like cushioning or dunnage product. This conversion may be accomplished by a cushioning conversion machine, such as that disclosed in commonly assigned U.S. Pat. No. 5,123,889. The conversion machine disclosed in U.S. Pat. No. 5,123,889 converts sheet-like stock material, such as paper in multiply form, into relatively low density pads. Specifically, the machine converts this stock material into a continuous unconnected strip having lateral pillow-like portions separated by a thin central band. This strip is coined along its central band to form a coined strip which is cut into sections, or pads, of a desired length. The stock material preferably consists of three superimposed webs or layers of biodegradable, recyclable and reusable thirty-pound Kraft paper rolled onto a hollow cylindrical tube. A thirty-inch wide roll of this paper, which is approximately 450 feet long, weighs about 35 pounds and will provide cushioning equal to approximately sixty cubic feet of plastic foam peanuts while at the same time requiring less than one-thirtieth the storage space.
The converting machines known in the prior art, including the one shown in U.S. Pat. No. 5,123,889, have utilized a guillotine type cutter to sever the coined strip into sections of the desired length.
The present invention provides an improved cutter mechanism for cushioning conversion machine which is able to sever a converted strip of cushioning in an efficient and effective manner. In one embodiment of the present invention the cutting mechanism includes a rotating, circular blade mounted for movement along a track which is transverse to the path of the converted strip of cushioning through the machine. The blade preferably is driven by an attached gear which engages a fixed rack. As the blade traverses the paper path, the cutting edge turns faster than rolling contact, causing a severing action.
In a second embodiment, the cutting mechanism includes a knife mounted for movement along a track which is transverse to the path of the converted strip of cushioning though the machine. The cutting edge of the knife is slanted, and the tip of the blade rides in a slot which is parallel to and below the track. As the knife is drawn across the paper, the sharp edge presses the paper downward toward the slot until there is enough pressure to force the knife through the paper severing the strip into sections of the desired length.
In a third embodiment, a wire is positioned below the path of the converted strip of cushioning through the machine. A shearing bar which includes a lengthwise slot is positioned above the path of the converted strip of cushioning through the machine. The wire can be lifted through the slot by a pair of hooks which extend through the slot and straddle the strip. When first one hook and then the other are lifted, the sharp, thin wire shears the paper as the wire passes through the slot.
In a fourth embodiment, the cutting mechanism includes an opposed pair of knife edges, one of which is mounted for vertical movement across the path of the strip of converted paper through the machine, and the other of which is fixed below the path of the strip. A lever, crank and connecting rod actuate the moveable knife edge and bring it into forceful contact with the fixed blade to sever the strip of paper.
In a fifth embodiment, the cutting mechanism includes a pair of serrated blades mounted side-by-side. The blades are movable along vertical tracks located on opposite sides of the path of the converted strip through the machine. Each track also includes a zigzag cam which engages and drives a cam follower connected with one of the blades. The cams are positioned so that the blades oscillate with respect to each other as they move downward through the converted strip.
These cutting mechanisms are used as part of a cushioning conversion machine which converts sheet-like material into a relatively low density cushioning dunnage product. A preferred machine comprises initial and subsequent units having separate housings. The initial unit includes in the housing thereof a shaping member over which the sheet-like stock material is drawn to form the stock material into a three-dimensional shape. The subsequent unit includes in the housing thereof a feed mechanism for drawing the stock material over the shaping member of the initial unit. The housings of the initial and subsequent units respectively have an outlet opening and an inlet opening relatively positionable with respect to one another to provide a pathway for transfer of the sheet-like material from the initial unit to the subsequent unit. The cutting mechanism is mounted in the subsequent unit for cutting the cushioning dunnage product into cut sections.
The present invention provides the foregoing and other features hereinafter fully described and particularly pointed out in the claims, the following description and annexed drawings setting forth in detail certain illustrative embodiments of the invention, these embodiments being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.